Pneumatic tire having improved wet traction

Abstract

A directional pneumatic tire having improved wet traction has an annular aqua channel and curved lateral grooves which direct water from the footprint to the shoulder area of the tire to help prevent hydroplaning. The pitch boundaries between the portions of the tire on either side of the aqua channel may be skewed. The curved lateral grooves and the skewing reduce noise properties of the tire. In addition, the lugs may have rounded or radiused leading and trailing edges, and a leading groove wall angle of about 5° and a trailing groove wall angle of about 1°, which are believed to reduce noise and irregular wear. The lugs contain slots which change direction within the lug and tie bars in the slots at each point where the slots change direction. The tread has non-skid depth of 0.75 to 1 cm (0.030 to 0.40 inch) and a ratio of non-skid to tie bar depth of 0.42.

What is claimed is: 
     
       1. A tire for use on a paved surface comprising a tread having a footprint net-to-gross ratio of 50% to 70% and having lugs defined by lateral grooves and circumferential grooves wherein said lugs have a leading groove wall angle of 3° to 8° and a trailing groove wall angle of 0° to 2°, said tire having a footprint comprising two distinct contact patches when said tire is inflated and loaded at design pressure and load, each said contact patch having a substantially trapezoidal shape wherein the two contact patches are oriented longer base to longer base, wherein said contact patches are separated by a void area that comprises 10% to 20% of the footprint width, and wherein each contact patch demonstrates lateral grooves longer than the width of said contact patch. 
     
     
       2. The tire tread of claim 1 wherein said lugs have a leading groove wall angle of about 5° and a trailing groove wall angle of about 1°. 
     
     
       3. The tire tread of claim 1 in which said lateral grooves are arcuate wherein no two lugs along a lateral groove are in lateral alignment. 
     
     
       4. The tire tread of claim 3 in which said tire tread has means for separating said tread into at least two annular tread portions, wherein said portions are skewed such that no two lugs in said tire tread are in lateral alignment. 
     
     
       5. The tire tread of claim 1 wherein said lugs have radiused leading edges. 
     
     
       6. A tire for use on a paved surface comprising a tread having a footprint net-to-gross ratio of 50% to 70% and having lugs defined by lateral grooves and circumferential grooves wherein said lugs have a leading groove wall angle of 3° to 8°, said tire having a footprint comprising two distinct contact patches when said tire is inflated and loaded at design pressure and load, each said contact patch having a substantially trapezoidal shape wherein the two contact patches are oriented longer base to longer base, wherein said contact patches are separated by a void area that comprises 10% to 20% of the footprint width, and wherein each contact patch demonstrates lateral grooves longer than the width of said contact patch. 
     
     
       7. A tire for use on a paved surface comprising a tread having a footprint net-to-gross ratio of 50% to 70% and having lugs defined by lateral grooves and circumferential grooves wherein said lugs have a trailing groove wall angle of 0° to 2°, said tire having a footprint comprising two distinct contact patches when said tire is inflated and loaded at design pressure and load, each said contact patch having a substantially trapezoidal shape wherein the two contact patches are oriented longer base to longer base, wherein said contact patches are separated by a void area that comprises 10% to 20% of the footprint width, and wherein each contact patch demonstrates lateral grooves longer than the width of said contact patch.